Oxidation of lower aliphatic alcohols



July 11, 1944. D c HULL 2,353,160

OXIDATION OF LOWER ALIPHATIC ALCOHOLS Filed June 29, 1942 METER CONDENSER 27 STEAM 1 2! T 21* 1 W \k /za SEPARATOK 24 oxwATmu UNIT ,,-PACKED 2T 7 22 SCRUBBER RECEIVER 1 1 e .14 .L Y RECEIVER L w OXIDIZING MEDIQM I, DAV") C .HULL

I INVENTOR ATT EYS Patented July 11,1944

UNITED sTA'i Es PATENT orrics OXIDATION are 1 2 ALIPHATIC David 0. Hull, Kingsport, rem, assignor to East-' man Kodak Company, Rochester, N. Y., a corporation of New Jersey Application June 29, 1942, Serial'l'lo. 448,960

. 3 Claims.

This invention relates to the direct oxidation of organic compounds, particularly the oxidation of hydroxy compounds such as lower aliphatic alcohols oxidized directly to acids.

This invention is a continuation-in-part of my allowed application, Serial No. 228,822, filed September 7, 1938, now Patent No. 2,287,803.

As, pointed out in connection with the aforementioned companion application, in the prior art oxidation processes have required employing relatively high temperatures such as 300 C. or 400 C. and the application of several steps. In other words, the oxidationeither has not been direct, or if there has been direct conversion, the

, but also to a different acid.

single step. Still another object, however, is to provide a process which may also be applied to, not only the monohydroxy alcohols, but'to the polyhydroxy alcohols and other similar organic compounds. Another and particular object of this invention is to provide a direct'oxidation process which may be operated at relatively low temperatures and under ordinary pressure conditions, yet give very satisfactory yilds of the desired oxidation products. Still another object is to provide a direct oxldation'prooess for the conversion of alcohols to acids wherein the alcohol may be converted, not only to an acid having a n'umber of carbon atoms corresponding to the number of carbon atoms in the alcohol molecule,

7 A still further object is to provide a process which may be operated under other than normal atmospheric conditions,

namely, under either superatmospheric or reduced pressures.

A further object is to provide adirect oxidation process that may be applied to either alcohols with the prior art possesses a number of disadvantages exemplified, for example, by the required use of relatively high temperatures. Also there may in some instances be the disadvantage of polymerization of the products of the starting alone or mixtures of alcohols and aldehydes, or other types of mixtures. A still further object is to provide a direct, low-temperature oxidation process which may be applied to various mixtures materials accompanied by low yields and other 1 losses.

In my companion application aforesaid I have described a process for a more direct oxidation of organic compounds. While the process of my application functions very satisfactorily and gives good yields in relatively few steps, it involves the utilization of metals having an atomic number from 25 to 29. It is, therefore, apparent that it is desirable, particularly under present conditions, to develop a process in order that other metals may be employed and the process improved in other respects, as will be apparent from the description which follows.

After further investigation I have found that there are certain other catalytic materials which may be employed in direct oxidation processes in a manner akin to the procedure set forth in my companion application which not only permits obtaining direct oxidation, but permits the production of a relatively larger variety of products than has heretofore been obtainable. i This invention has for one object to provide a i process for the direct oxidation of organic compounds, Another object is to provide a direct oxidation process which is particularly valuable for the direct conversion of lower aliphatic alcohols to lower aliphatic acids in substantially a of alcohols and aldehydes wherein both the alcohol and the aldehyde are converted into useful oxidation products. Another object is to provide a direct oxidation process, particularly adapted to the treatment of alcohols such as butyl alcohol and the like wherein, not only may butyricacid be obtained, but contents of other acids.

' first dehydrogenated and thzifthe dehydrogenation products further treated. In any event prior art processes as applied to alcohols usually involve the utilization of temperatures in excess of,

300 C. which, not only requires substantial heat input but,'due to the higher temperatures and other conditions required in handling chemicals, involves dangers of .loss from polymerization or other undesired reactions. Also apparatus destruction may be more severe.

I have found that contrary to suchprocedure an organic compound, exemplified in particular by a hydroxy compound as a lower aliphatic alcohol, may be directly oxidized at relatively low temperatures, even temperatures subtantially below 100 C., with any of the usual oxidizing mediums of which the commonest one, namely air, may be readily utilized in my process. Also my process, after it is placed in operation, does not *psually require any heat input but generates sufficient heat itself to maintain the reaction. Not only may single organic compounds be treated, but various mixtures of the organic compounds may be treated. For example, I have found that a mixture comprising a lower aliphatic alcohol; together with a corresponding or a different aidehyde, may be efficiently treated by my novel process and catalyst to give very high yieldsof aliphatic acid. By my process and choice of catalyst it is possible to obtain one or more acids in the oxidation procedure. The foregoing features, as well as features of treating various mixtures under different conditions, will be set forth in detail hereinafter.

While the oxidation procedure may be carried out in the apparatus described in the aforesaid companion application 228,822, now Patent No. 2,287,803, for convenience of consideration and for a better understanding of the present invention reference will be made to the attached drawing. The attached figure may be considered a semi-diagrammatic side elevation view showing a general apparatus arrangement which could be employed for carryirfg' dut my process.

Referring to the drawinggZ represents an oxidation unit which may comprise any of several different constructions. For example, the preferred external construction would, in. a large diameter unit, be in accordance with Hasche Patent 2,159,988. However, the construction may be a sieve plate column, bubble plate column, or other comparable arrangement for permitting the contact of an oxidizing medium containing free oxygen with the material to be oxidized. In the unit shown in the attached figure the column. merely comprises an elongated, open column of relatively narrow dimensions. Attached; to the lower part, of the unit at t and E, are cooling jackets provided with inlets for cooling medium as at 6 and l.

The upper part of the unit was provided with a similar Jacket 8; however, in this jacket, rather than cooling medium some heating medium may be circulated in the event that high boiling components are being directly oxidized or the reaction temperature is to be held lower than that which would maintain a constant volume of catalyst. Inasmuch as the construction is substantially the same, however, the mechanical construction would be approximately the same and an inlet provided at 9, i and S; outlets are pro vided at H, I2, and lil.-'

As indicated, if desired in place of the external jackets, coils may be included within the unit and in large-size units such arrangement wherein internal coils,- or both coils and jackets are em ployegl, may be desirable.

The lower part of the unit is provided with a plurality of inlet conduits, namely, inlet conduit l4 which is connected with a temperature-con .trolled feed supply it. Also leading into the lower part of the unit is an inlet conduit l'i for oxidizing medium.

The upper part of the unit is provided with a drawoif conduit it which ieads through on denser is into separator separator has attached thereto a receiver for condensate There may also be associated with. the appa ratus thermometers or other temperature controlling devices or various exchangers for recovering heat or otherwise facilitating or rendering the operation of the process more economical, or permitting it to be operated with automatic control. Hence, my invention is not to be restricted in these respects.

I have found that certain metal compounds, as for example, esters derived from metals of the so-called refractory metals group including chromium, molybdenum, tungsten and uranium may be incorporated in acid solutions and that these solutions will function as a catalyst medium for the direct oxidation of organic compounds. That is, an alcohol alone or alcohol and other organic compounds to be oxidized, may be passed into a catalyst solution, as aforementioned, in th presence of oxidizing medium containing free oxygen and that the alcohol may be directly oxidized to acid, as will be observable in greater detail from the specific examples which follow.

In preparing catalyst solutions for use in the present process any convenient source of the metal may be employed, such as salts, oxides or other derivatives thereof. Preferably, a derivative would be chosen which is easily soluble under conditions prevailing in the process. For example, assuming that it is desired to convert an alcohol such as ethanol or butanol directly to the corresponding aliphatic acid, the derivative of the catalyst metal would preferably be chosen corresponding to this acid. Specifically, in the instance of producing acetic acid, there may be employed metal compounds such as molybdenum, vanadium, thorium, chromium and uranium acetates, depending upon the particular metal or metals selected.

Further examples of metal derivatives which may be employed for producing the catalyst solu- 7 tion are chromium propionate, uranium butyrate,

cohol directly'into butyrlc acid I would preferably dissolve the catalyst compounds in an all phatic acid such as butyricacid. However, propionic or acetic acid could also be used. However, for initially preparing the catalyst solution other liquids could be employed, as for example, organic esters and the like such as butyl or ethyl acetate.

In any event, irrespective of the exact metal compound and the liquid that the compound is dissolved in, the catalyst solution would be given a vigorous oxidation treatment such as blowing with a substantial amount of air usually for a period of at least 5 or 10 minutes, and if desired for several hours. This treatment would preferably be accompanied by the introduction of an For example, in the event my aldehyde along with the oxidising medium and amount to a saturated solution, but in general functions to convert the metal ions of thecatthe amount of catalyst will be maintained beaiyst metal into a higher state of valence than tween 1% or 2% and 12%.

their lowest valence. The treatment may be ac- While the foregoing examples are illustrative I companied by heating obtained'ln any convenient 5 of one of the preferred application's ofmy process, manner such as by flowing a heating medium my process may be operated with the various in the jackets or coils in association with the other catalysts referred to and under various oxidation unit or by introducing heated air. The other conditions, as will be apparent from the mperatui'e of treatment, however, may vary examples which follow:

from around -5 C. up to the boiling point of Example I" the particular liquid present. In other words the solution is maintained under liquid phase In accordance with this example a li 8 conditions. M solution is composed of 100 parts of acetic acid It is also preferred to incorporate the oxidizhaving dissolved in -1 part of ybde u ing medium into the catalyst liquid under at least acetate, pe Vanadium acetate. n atmospheric pressure as this permits the inclu- Part8 thorium -t vT1118. eelutlOn 18 msion of a larger amount of oxidizing medium and D fl 88 p w described W h f f 1.000

fully saturates the catalyst liquid. B 0 hy 94111 5 8 8m8 K130111 81 After the catalyst liquid containing a metal b y al hol- 011 this ratio is obtained an averselected from the refractory group of metals as 20 88 y ld 0! 50-490 drama ot butyric acid and specified above, has been treated and brought to 0-20 grams of D pionic acid as the male P a starting temperature, usually above room tem- 110m f the Oxidation P c As n the p perature, but below around 100 C., the organic ins examples the proc w Op rated so that compound to be oxidized may be supplied to the the catalyst Solution W88 al e i the quid process. phase. However, in the instance of alcohol, as That is, referring to the attached drawing, the tyl alcohol, it is po s if it IS e i ed to oxidation column 2 is filled with the catalyst Operate th t pe ures up to near y 150 C.,

liquid comprising one or more metals oi the rethat higher temperature 0811 be p yed iractory group as above specified dissolved in Pressure 18 pp to e act on- In this rethe solvent and maintained at the desired tem-' action some excess oxldlzinfl medium (air) perature. The hydroxy compound tobe oxidized be supplied to the reaction so that a content is introduced into, the oxidation process through of oxysen was indicated in the oil Ba es.

conduit 14 and the oxidizing medium, usually en et y a co o or p opyl alcohol is used air (however, pure oxygen or ozone may be em- Place Of in admixture with bu y o o ployed and appear to render the catalyst solu- 5 lower temperatures y be p y urthertion more active, but are not necessary), and the more, the P e y be Va ed Within rather compound oxidized to one or more desired oxida- Wide limits Without-basically c nsins the p Oetion products, as will be described hereinafter. $1m1lal1y; the catalyst y be mp yed 88 Assuming that the oxidation product is a liquid, a salt or mixt 0! Salts of 8 O a c acid or a portion thereof may be. volatilized or pumped 40 801.58. mixture 01 the metals themselves y off through conduit I8 through the condenser I! be mp oyedwhere condensables are condensed out to be 001- In. the foregoins example ther wa some 81- lected in receiver 2-2. 'Theunconsumed gases (as eOhOl left h n d whi h may be recovered nitrogen whe ir-1 se i l izm medium) either, in the scrubber or otherwise. As indiunoxidized organic compound and the like com-' sated. while at normal o p r c p e sure a ponents, uncondensed, pass through conduit 23 temperature under Imd in ininto scrubber 24 where they are recovered. stances between a-lld C" pp t While only asingle scrubbing unit has been inbe quite s t t athe process may be caused I dicated, a plurality of such units may be emto Ope at even at temperatures as low as 5 C.

ployed or other recovery devices utilized. #5 d p to the boiling p i t f the catalyst solu- The operation of my process to convert an tion- I v organic compound such as butyl alcoholto ali- In preferred operation using, for example, the

phatic acids and the functioning of various of i as an oxidant, this may be supplied under the refractory group of metals as above specified some pressure and if desired a rather substanas catalysts is believed quite clearly illustrated tial excess canbe incorporated, although for by the data appearing in the following table: normal operations a slight excess, merely so that 3 els Yg eishf Weisht Percent Percent i w won mi "as" e? "mar- 3 on fed produced produced .35 acid r i F 1. Chromium... 1.2 sec 1.000 am as us 1.1: 51.1 1.31 was 1.63

: II. Uranium--. 4 468-8 939.2

' The foregoing examples were carried out in a few per cent of.oxygen are indicated in the apparatus as indicated in the attached drawlns eiiluents, would be employed. In the event of the and at a temperature between 30 C. and 50 C. use of other oxidants such as relatively pure' f It will be observed that the catalyst indicated oxygen and ozone, smaller amounts arerequired gave yields of propionic acid in addition to and may be supplied under substantial pressure butyric acid, although butyl alcohol and acetaldefor causing them to fully permeate the entire hyde were the materials processed. While a catalyst solution.

1.2% to 4% catalyst solution has beenindicated, theamount of catalyst may vary from a small While in certain of the foregoing examples we have indicated'the utilization of butyl alcohol in ture of ethyl alcohol and butyraldehyde may be I procemed in the-same manner to obtain a mixture of acetic and butyric acids. Similar remarks apply to the employment of other mixtures of alcohols and aldehydes. That is, ethyl alcohol may be processed in admixture with acetaldehyde to produce relatively pure" acetic acid. Or, for example, propyl alcohol may be processed in accordance with the present inventlon in the presence of acetaldehyde, butyralde hyde, or propionaldehyde. However, inasmuch a acetaldehyde is in many instances most readily available and has a low boiling point, it would preferably be employed along with the other alcohols such as butyl alcohol, amyl alcohol, and the like as representing the most economical procedure as well as tending to lower the boiling points and permitting the functioning of the process at lowest temperatures.

As already indicated, the pressure may be varied over wide limits without basically the process. However, since the process functions satisfactorily under normal atmospheric pressures I prefer to operate under such conditions except that in some instances, such as for saturating the catalyst solution with omen, I may apply a few pounds pressure up to 2 or 3 atmospheres for this purpose. Also, as indicated, the process functions very well at ordinary temperatures of 30 C. to 50 C. However, by raising the temperatures above the range indicated and applying some increased pressure, larger amounts of alcohol may be converted per pass per unit of time. Under such procedure the aldehyde feed would be correspondingly reduced as the amount of alcohol fed was increased.

As apparent fromcertain of the preceding examples one valuable aspect of the present invention is that acids having fewer carbon atoms than the alcohol being oxidized may be directhr produced and the proportion of these other acids to the acid having the same number of carbon atoms as the alcohol being oxidized may be varied by choice of the particular catalyst, as apparent from Examples I, II and HI set forth above.

It is apparent from the foregoing that my invention is applicable to the direct oxidation of the various organic compounds, particularly hydroxy compounds such as various alcohols. The foregoing examples are merely illustrative of some ofthematerialstowhich mylowtemm ture liquid phase process may be applied, but various other compounds, such as hydroxy alcohols exemplified by glycols, may be treated in a comparable manner; Hence, I do not wish to be restricted in my invention excepting insofar as is necessitated by the prior art and the spirit of the appended claims. v

'WhatIclaimanddesiretosecurebyLetters Patent of the United States is:

l. A process for the direct oxidation of a lower aliphatic alcohol to obtain the corresponding aliphatic acid, which comprises treating a solution of a metal ion of a metal of the chromium group in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to form a catalyst aliphatic acid, which comprises treating a solution of a metal ion of a metal of the chromium group in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to forma catalyst solution, introducing material amoimts of a lower aliphatic alcohol and a lower aliphatic aldehyde into the activated catalyst solution, oxidizing the alcohol of the resulting solution of catalyst, alcohol and aldehyde by treating said solution with a gaseous oxidizing medium, maintaining the temperature of the solution of catalyst, alcohol and aldehyde during its treatment with the gueous oxidizing medium such that the solution is maintained in the liquid phase at a temperature of from --5 to C. and subsequently recovering the aliphatic acid produced.

3. A process for the,direct oxidation of a lower aliphatic alcohol to obtain the corresponding aliphatic acid. which comprises treating a solution of chromium salt in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to form a catalyst solution, introducing material amounts of a lower aliphatic alcohol and a lower aliphatic aldehyde into the activated catalyst solution, oxidizing the alcohol of the resulting soluthat the solution is maintained in the liquid phase below 150 0., and subsequently recovering the aliphatic acid produced. DAVID C. HULL. 

